libi3: Make visual_type extern

See #3914

i3-config-wizard/main.c

@@ -68,6 +68,7 @@
     } while (0)
 
 #include "xcb.h"
+xcb_visualtype_t *visual_type = NULL;
 #include "libi3.h"
 
 #define TEXT_PADDING logical_px(4)

i3-input/main.c

@@ -8,8 +8,6 @@
  *                  to i3.
  *
  */
-#include "libi3.h"
-
 #include <stdio.h>
 #include <sys/types.h>
 #include <stdlib.h>
@@ -27,6 +25,9 @@
 #include <xcb/xcb_event.h>
 #include <xcb/xcb_keysyms.h>
 
+xcb_visualtype_t *visual_type = NULL;
+#include "libi3.h"
+
 #include <X11/keysym.h>
 
 #include "keysym2ucs.h"

i3-nagbar/main.c

@@ -8,8 +8,6 @@
  * when the user has an error in their configuration file.
  *
  */
-#include "libi3.h"
-
 #include <stdio.h>
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -32,6 +30,9 @@
 #include <xcb/randr.h>
 #include <xcb/xcb_cursor.h>
 
+xcb_visualtype_t *visual_type = NULL;
+#include "libi3.h"
+
 #define SN_API_NOT_YET_FROZEN 1
 #include <libsn/sn-launchee.h>
 

libi3/draw_util.c

@@ -16,7 +16,7 @@
 #include <cairo/cairo-xcb.h>
 
 /* The default visual_type to use if none is specified when creating the surface. Must be defined globally. */
-xcb_visualtype_t *visual_type;
+extern xcb_visualtype_t *visual_type;
 
 /* Forward declarations */
 static void draw_util_set_source_color(surface_t *surface, color_t color);